Pentair IC40 reading zero salt


Active member
Jan 30, 2019
Our pool was just refilled and our SWG is reading 0 PPM salt and the red “low salt” light is on. The proper salt level in the water has been verified. Our pool is 11,200 gallons and 8 bags of salt have been added/11.2k gals. Thinking this had something to do with the cold temps (water is around 52-53 degrees), I heated the spa up to 70 degrees and the same symptoms occur. Also, I have totally shut down all power to the EasyTouch panel and SWG multiple times in an attempt to reset it, to no avail. I also gave it a diluted acid rinse. From reading other posts, it sounds like there is a switch in the SWG that can go bad. If so, it’s still under warranty. Any other tips/thoughts before I open a warranty ticket?
Last edited:


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

If the water was too cold the only light the IC40 would have is the red "Cold Water Shut Off"

The fact that the water is known to have the right amount of salt, and that the IC40 has a red low salt light, point to a bad thermistor inside the Flow Switch assembly. This is an easy DIY fix, but if the unit is still under warranty you should let Pentair, or your pool builder, take care of it.


Jim R.
  • Like
Reactions: cybertoad


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
You would think after all these flow switch problems they would fix the problem. Rediculous. I had one go out as well after one year.
Pentair seemed to change the design of their Flow Switch from 4 wires to 3 wires on cells manufactured from September 2018. We will see if the new one works better then the old design.